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https://issues.apache.org/jira/browse/HDDS-2382?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Siddharth Wagle reassigned HDDS-2382:
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    Assignee: Siddharth Wagle

> Consider reducing number of file::exists() calls during write operation
> -----------------------------------------------------------------------
>
>                 Key: HDDS-2382
>                 URL: https://issues.apache.org/jira/browse/HDDS-2382
>             Project: Hadoop Distributed Data Store
>          Issue Type: Bug
>          Components: Ozone Datanode
>            Reporter: Rajesh Balamohan
>            Assignee: Siddharth Wagle
>            Priority: Major
>              Labels: performance
>
> When writing 100-200 MB files with multiple threads, observed lots of 
> {{[file::exists(])}} checks.
> For every 16 MB chunk, it ends up checking whether {{chunksLoc}} directory 
> exists or not. (ref: 
> [https://github.com/apache/hadoop-ozone/blob/master/hadoop-hdds/container-service/src/main/java/org/apache/hadoop/ozone/container/keyvalue/helpers/ChunkUtils.java#L239])
> Also, this check ({{ChunkUtils.getChunkFile}}) happens from 2 places.
> 1.org.apache.hadoop.ozone.container.common.transport.server.ratis.ContainerStateMachine.lambda$handleWriteChunk
> 2.org.apache.hadoop.ozone.container.common.transport.server.ratis.ContainerStateMachine.lambda$applyTransaction
> Note that these are folders and not actual chunk filenames. It would be 
> helpful to reduce this check, if we track create/delete of these folders.



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